Steam-ejector.



M. LEBLANC.

STEAM EJEGTOR. APPLICATION FILED APB. 9, 1913.

1,079,1 34, Patented Nov. 18, 1913.

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rUNITED STATES PATENT OFFICE.

MAURICE LEBLANC, OF VAL SUR SEINE PAR CROISSY, FRANCE, ASSIGNOR T0 STE. AME. POUR LEXPLOITATION DES PROCEDES WESTINGHOUSE LEBLANC, 0F PARIS,

FRANCE.

STEAM-EJECTOR.

Specification of Letters Patent.

Patented Nov. 18,1913.

To all 107mm t may concern.'

Be it known that I, MAURICE LEBLANC, a citizen of the Republic of' France, residing in Val sur Seine par Croissy, Seine-et-Oise, France, have invented certain new and useful Improvements in Steam- Ejectors, of which the following is a specification.

This invent-ion relates to steam ejectors and has for its object to provide an apparat-us of this nature which may be both started and operated under the best conditions o'f steam consumption and efficiency.

It is well known that the dimensioning o1' certain parts of an ejector designed to withdraw a fluid in an inclosed space at .the pressure p and to force it into an inclosed space at the pressure I?, should vary with the pressures p and I), also that the cross-section ot' the neck of the nozzles into which the motive steam is projected should vary with the ini tial pressure ot' the steam. In general the ejector should produce at starting the ditference of pressure which it is required to maintain afterward. This difference inf creases gradually from zero until the pressures 7J and P have acquired their normal values.

If the dimensioning of an ejector has been carried out with a view to obtaining the best possible efficiency during normal running, the ejector' cannot be properly dimensioned for starting under favorable conditions, be-

cause the ratio which at starting is equal to 1 ought to be greater in normal running. Again the ejector does not start it the nor mal value of the ratio exceeds a certain limit.

In order to cause the ejector to start, according to one method its dimensions are temporarily varied and are brought gradually to their normal values when once the start-ing is obtained. According to another method the pressures p and P are artificially varied at starting and the normal dimen sions of the ejector are made suitable for the new pressures thus obtained. Several arrangements for carrying out both of these methods have already been patented by the applicant.

The present invention relates to an nnproved ejector which is started by the first method above mentioned and which is characterized by the Yfact that the variation of its dimensions and output is effected by varying the number, distribution, and output of the several jets of motive steam.

The only movable or flexible parts which this improved ejector requires are simple valves the manipulation of' which suffices to obtain the desired variations of dimensions and output. The arrangements for regulating this improved apparatus are therefore very simple and experience has shown that they are completely effective.

In order that the invention may be clearly understood a practical embodiment of the same will now be described with reference to the accompanyingdrawings in which- Figure l shows diagrammatically the essential parts oit' the improved eject-or arranged according to this invention, and F ig. 2 illustrates a n'iodification.

Iteierring to F ig. l of the drawings, motive steam is supplied to the space A where the steam jets act upon the fluid to be withdrawn, by a large number of converging diverging nozzles such as those represented at B1, BL., Bm IL. These nozzles are distributed in concentric crowns which are shown in the drawing as being four in number. In order to simplify the description it will be supposed that the exit orifices ot' these nozzles all have the same cross-section; but it is to be understood that this is not necessary in practice. T he fluid to be withdrawn flows into the space A through a pipe (l, while opposite the exit orifices of the nozzles is the opening ofE a converging-diverging diffuser D which opens into the space into which it is desired to t'orcc the fluid which has been withdrawn by the pipe C.

In the improved ejector all the nozzles B of the same crown are fed with steam from one steam chamber which is separate from any other steam chamber, these steam chambers, to the number of four as shown in Fig. l, eorreslmnding to the four concentric crowns ot' nozzles, being represented at E1, E2, Em EV The motive steam is supplied to each of these steam chambers by one of the pipes F1, F2, Fm F4, and each of these pipes is connected to the main steam pipe G, and is provided with a valve H1, H2, H3, H4. The steam pressure prevailing in each pipe F beyond the corresponding valve H is indicated by the corresponding steam gage Il, I2: I3: I@

By means of the connections and valves above described steam at any desired pressure (up to that of the steam in the main pipe G) can be supplied to the nozzles of any one of the crowns and this pressure may be different from the pressure of the steam supplied to the nozzles of any other crown.

The neck, that is, the part of the nozzle where the converging portion meets with the diverging portion, is given the same crosssection in the case of all the nozzles of one and the same crown, but the cross-section of the necks of one crown of nozzles is made different from that of the necks of any other crown of nozzles. The applicant has found by experiment that there is an advantage in giving the greatest cross-section to the necks of the nozzles of the outer crown and in reducing this cross-section proportionally to th-e reduction of the diameters of the successive crowns.

In normal running all the nozzles of the ejector will be in operation and as they are all supposed to have exit orifices of the same cross-section they should therefore have substantially the same output. Hence the various nozzles should be fed with steam at a lower pressure in proportion as their necks have a greater cross-section. Under these conditions the pointers of the steam gages Il, I2, f3, L, will occupy different positions as shown in the drawing; the correct steam pressure for each crown of nozzles may be marked on the dials of the steam gages.

rThe exit orifices of the nozzles should always be given such cross-sections that, during normal running, the steam issues from them with a pressure somewhat higher than the pressure p which it is desired to maintain in the space A. At starting the pressure in this space will generally be equal to P and, to simplify the description, this pressure will be supposed to be constant. In order that the steam may issue at a high speed from the nozzles it is necessary that its pressure should not drop at that point below the pressure P, as is demonstrated in the work of Stodola on Steam turbines.

The above condition will be approximately fulfilled in practice by sending all the available steam into the nozzles of the outer crown alone, that is, by opening wide the valve lf-l1 and closing all the others, as their necks have a cross-section greater than that of the necks of the other nozzles. It has been found that under these conditions the pressure p drops and acquires a value 791 smaller than the pressure P. The valve H1 is then gradually closed to some extent and the valve H2 is opened, in such a manner that all the available steam continues to pass through the nozzles of the two first crowns and this operation is continued until the pressures indicated by the gages l1 and l, show that the nozzles of the said two crowns have the same output. It is then observed that the pressure in the space A acquires a new value p2 lower than the value p1, and

SOv O11.

ln the above described operation ejectors having only one crown, two crowns, and so on, of nozzles are successively brought into use but always consuming the same quantity of motive steam, that is, the ejector having one crown is gradually transformed into an ejector having two "crowns, and so on, in proportion as the pressure is reduced in the space A; hence the output of the nozzles in service is greater in proportion as they issue into a medium at a higher pressure thus enabling the jets of steam issuing from them to have a speed sufficient to pass the diffuser' without being too much expanded and without occupying all the cross-section of the diffuser, which otherwise would render the flow of the withdrawn fluid impossible. To facilitate the operations a suitable number of marks may be provided upon the dials of the steam gages to indicate the positions which their pointers ought to occupy according as there are one, two, three or four crowns in service.

in addition to the arrangement of nozzles described above, the applicant has also tested an ejector in which the steam was first supplied to the central nozzles, which for this purpose were given necks of a large cross-section and in some cases this crosssection was made variable by means of movable needles. This arrangement however has not furnished such good results as that first described above. It is probable that the withdrawing action of the jet projected by the central nozzles combined with the retarding action of the walls produces a whirling ring which incloses the jet and takes work from it thus causing its rapid expansion. This phenomenon is not produced in the interior of the hollow jet constituted by the assemblage of the jets issuing from the nozzles of the exterior crowns, as the ret-arding action of the walls does not appear to have any effect in the interior of this hollow jet.

lt has been found that in order to start the improved ejector it is generally suii'icient to send the steam only into the nozzles of the exterior crown; when the pressure has once been brought to the value p1, if the steam is so regulated as to bring the pointer of the gage l, to the position corresponding to normal running the pressure in the space A takes a new value 791 smaller than p1 and sufficiently low to enable the ejector to definitely start and be brought to normal running by opening simultaneously the valves H2, H3, and H4. Owing to this fact the applicant has developed the modification shown in Fig. 2, which is a simpler construe-I tion than that shown in Fig. 1, as it only comprises two separate steam supply pipes although the nozzles may be distributed in any number of concentric crowns. This form of the improved ejector generally starts easily and all its interior crowns of nozzles connected in parallel may have necks of the same cross-section provided that they have exit orifices of the same cross-section.

The invention is not limited to the precise number or arrangement o't' separate steam supply pipes describedhereinabove and illustrated in the drawings, as it is evident that any desired number ot such separate steam supplies may be employed and these may be arranged to feed each, or any desired number, of the nozzles of one or more concentric crowns, without departing from the scope of the invention.

Vhat is claimed is:

1. A steam ejector comprising a plurality ot' separate steam chambers, a group of nozzles secured in each steam chamber for projecting steam upon the l'luid to be withdrawn, and means for supplying steam at different pressures to the several steam chambers.

2. A steam ejector comprising a plurality of coaxially arranged separate steam chambers, a separate group of nozzles fed from each steam chamber for projecting the motive steam upon the fluid to be withdrawn, a pipe connecting each steam chamber with a main steam supply, and means in each pipe ot' the nozzles being constant within each group but dili'erent in the dii'lerent groups, steam pipes for separately supplying steam to each steam chamber, and means 'for varying the output of the nozzles with variation in the pressure of the medium into which they exhaust.

4. In a steam ejector, a plurality of separate steam chambers, a plurality of nozzles grouped in each steam chamber, the nozzles of one group being differently dimensioned relatively to those of another group, a separate steam pipe for supplying steam to each steam chamber, a pressure regulating valve in each steam pipe, and means for indicating the most favorable pressure oi steam to supply to each group of nozzles under the varous conditions of starting and running.

In witness whereof, I have hereunto signed my name in the presence of two subscribing witnesses.

MAURICE LEBLANC. lVitnesses:

IIANSON C. Coxn, GABRIEL BELLIARD.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

